The purpose of this trial is to investigate the safety and efficacy of leflunomide for the treatment of 16 patients with uveitis, randomly assigned to treatment with placebo or leflunomide. This one year study is a double-masked, randomized, placebo-controlled intervention study. Patients receive 100 mg of study drug or placebo each day for three days, then 20 mg of study drug or placebo for the next 12 months. Patients and clinic staff will be masked to treatment assignments. All patients, regardless of treatment assignment, will placed on prednisone at a dose of 1 mg/kg/day, not to exceed 80 mg qd. Randomization will be stratified by current use (within two weeks of randomization) of prednisone at a dose > 10 mg qd versus current use (within two weeks of randomization) of prednisone at a dose < 10 mg qd (including no prednisone use). Subsequent to randomization, prednisone will be tapered to 10 mg po qd over 16 weeks according to a standard schedule. Patients will be examined at baseline and at 1, 4, 8, 12, 16, 24 weeks, 9 and 12 months after beginning study medication. Primary study outcomes include a best corrected visual acuity decrease of 10 letters or more from baseline; inability to taper prednisone to 10 mg qd by Week 16; inability to maintain prednisone dose of < 10 mg qd from Week 16 through Month 12; addition of systemic therapy required to treat ocular inflammatory disease. Primary safety outcomes include the occurrence of at least one of the following: abdominal pain, diarrhea, skin rash, hypertension, or alopecia and additionally weight loss and changes in liver function tests will be described. Secondary efficacy endpoints will include the presence or absence of vitreous haze and cystoid macular edema.